<template>
  <div class="music-list">
    <div class="back">
      <i class="icon-back" @click="hanleBackSinger"></i>
    </div>
    <h1 class="title" v-html="title"></h1>
    <div class="bg-image" :style="bgImgStyle" ref="bgImage">
      <div class="filter" ref="filter"></div>
      <div class="play-wrapper" ref="playBtn" v-show="songs.length" @click="handleRandomPlay">
        <div class="play">
          <i class="icon-play"></i>
          <span class="text">随机播放</span>
        </div>
      </div>
    </div>
    <div class="bg-layer" ref="layer"></div>
    <scroll class="list"
     :data="songs"
     ref="list"
     @scroll="scroll"
     :probe-type="probeType"
     :listen-scroll="listenScroll"
     >
      <div class="song-list-wrapper">
        <song-list :songs="songs" @selectSong="selectItem"></song-list>
      </div>
      <div class="loading-container" v-show="!songs.length">
        <loading></loading>
      </div>
    </scroll>
  </div>
</template>

<script>
import Scroll from '@/base/scroll/scroll'
import SongList from '@/base/song-list/song-list'
import {prefixStyle} from '@/common/js/dom'
import Loading from '@/base/loading/loading'
import {mapActions} from 'vuex'
const HEAD_HEIGHT = 40
// 给样式加上浏览器内核的前缀
const transform = prefixStyle('transform')
console.log(transform)
const backDropFilter = prefixStyle('backdrop-filter')
export default {
  components: {
    Scroll,
    SongList,
    Loading
  },
  props: {
    songs: {
      type: Array,
      default: function() {
        return []
      }
    },
    bgImg: {
      type: String,
      default: ''
    },
    title: {
      type: String,
      default: ''
    }
  },
  data() {
    return {
      scrollY: '', // 在y轴上滚动的距离
      probeType: 3, // 函数截流实时监听
      listenScroll: true // 监听滚动事件
    }
  },
  watch: {
    scrollY(newY) {
      let zIndex = 0
      let scale = 1
      let blue = 0
      let withScrollY = Math.max((HEAD_HEIGHT - this.bgImageHeight), newY)
      this.$refs.layer.style[transform] = `translate3d(0, ${withScrollY}px, 0)`
      // this.$refs.layer.style['webkitTransform'] = `translate3d(0, ${withScrollY}px, 0)`
      let percent = Math.abs(newY / this.bgImageHeight)
      if (newY > 0) {
        zIndex = 10
        scale = 1 + percent
      } else {
        blue = Math.min(20 * percent, 20)
      }
      this.$refs.filter.style[backDropFilter] = `blue(${blue}px)`
      // this.$refs.filter.style['webkitBackdrop-filter'] = `blue(${blue}px)`
      if (newY < (HEAD_HEIGHT - this.bgImageHeight)) {
        zIndex = 10
        this.$refs.bgImage.style.paddingTop = 0
        this.$refs.bgImage.style.height = `${HEAD_HEIGHT}px`
        this.$refs.playBtn.style.display = 'none'
      } else {
        this.$refs.bgImage.style.paddingTop = '70%'
        this.$refs.bgImage.style.height = 0
        this.$refs.playBtn.style.display = ''
      }
      this.$refs.bgImage.style.zIndex = zIndex
      this.$refs.bgImage.style[transform] = `scale(${scale})`
      // this.$refs.bgImage.style['webkitTransform'] = `scale(${scale})`
    }
  },
  computed: {
    bgImgStyle() {
      return `background-image: url(${this.bgImg})`
    }
  },
  methods: {
    ...mapActions({
      selectPlay: 'selectPlay',
      randomPlay: 'randomPlay'
    }),
    handleRandomPlay() {
      this.randomPlay({
        list: this.songs
      })
    },
    selectItem(song, index) {
      this.selectPlay({
        list: this.songs,
        index
      })
    },
    hanleBackSinger() {
      this.$router.back()
    },
    scroll(pos) {
      this.scrollY = pos.y
    }
  },
  created() {},
  mounted() {
    this.bgImageHeight = this.$refs.bgImage.clientHeight
    this.minTranslateY = -this.bgImageHeight
    this.$refs.list.$el.style.top = `${this.bgImageHeight}px`
  }
}
</script>
<style lang="stylus" scoped>
@import "~@/common/stylus/variable"
@import "~@/common/stylus/mixin"

.music-list
  position: fixed
  z-index: 100
  top: 0
  bottom: 0
  left: 0
  right: 0
  background: $color-background
  .back
     position: absolute
     top: 0
     left: 6px
     z-index: 50
     .icon-back
        display: block
        padding: 10px
        font-size: $font-size-large-x
        color: $color-theme
    .title
      position: absolute
      top: 0
      left: 10%
      z-index: 40
      width: 80%
      no-wrap()
      text-align: center
      line-height: 40px
      font-size: $font-size-large
      color: $color-text
    .bg-image
      position: relative
      width: 100%
      height: 0
      padding-top: 70%
      transform-origin: top
      background-size: cover
      .play-wrapper
        position: absolute
        bottom: 20px
        z-index: 50
        width: 100%
        .play
          box-sizing: border-box
          width: 135px
          padding: 7px 0
          margin: 0 auto
          text-align: center
          border: 1px solid $color-theme
          color: $color-theme
          border-radius: 100px
          font-size: 0
          .icon-play
            display: inline-block
            vertical-align: middle
            margin-right: 6px
            font-size: $font-size-medium-x
          .text
            display: inline-block
            vertical-align: middle
            font-size: $font-size-small
      .filter
        position: absolute
        top: 0
        left: 0
        width: 100%
        height:100%
        background: rgba(7, 17, 27, 0.4)
    .bg-layer
      position: relative
      height: 100%
      background: $color-background
    .list
      position: absolute
      top: 0
      bottom: 0
      width: 100%
      background: $color-background
      .song-list-wrapper
        padding: 20px 30px
      .loading-container
        position: absolute
        width: 100%
        top: 50%
        transform: translateY(-50%)
</style>